As it stands right now, the Electric Observer EB is based on our popular gas powered version of the Observer EB.

Obvious difference is the removal of the gas engine and drivetrain, and adapting an electric motor and drivetrain.

With the help of individuals like Greg Alderman, Rusty McClintock, and Clint Akins of Flightpower, we have been doing extensive testing to come up with the best, most efficient system, matching the available electric motors to the properly geared drivetrain, giving you a remarkable amount of flight time for an electric helicopter weighing in at appx 24 Lbs RTF weight with camera and batteries mounted.

Some not-so-obvious differences that you may find are areas of lightening the ship, using the Magnum tail gearbox and a thinner walled boom, using thinner material G10 on the lower frames with lightening holes incorporated, together shaving 3/4 Lb off of the flying weight, without sacrificing durability.

Of course we've kept all the good stuff, the all aluminum head, the fully push-pull control system, and the Legendary Bergen R/C Support is built into every kit made.

We have so far tested the Hacker A50-14 motor, and the Actro 32-4. Both have been tested with Li-Manganese batteries, 2 ea of 6s2p at 7600 Mah.

Different headspeeds have been tried. The Hacker motor, with appropriate gearing, seemed to like the lower headspeed of 1350-1400, giving a solid 15-17 minute flight time.

The Actro, again with appropriate gearing, prefered a higher headspeed 1450-1600, but only giving a 13 minute flight time. The helicopter itself flew very nice at this headspeed, I almost felt like rolling it!!

We are working on pricing, but expect it to be comparable to most large electrics with a camera mount added to the cost._________________Chris Bergen
Bergen R/C Helicopters

I understand that you need a 2 each of 6s2p Li-Mn batteries. They total either 7600 mAh or 15200 mAh at 22.2 V. That amount of energy will provide 15 minutes of flight. What is the average power draw during that time? 674 W? or 1350 W?

We'll be doing another test flight today, we've rewired the sytem so that we can read the total voltage and current draw.

The batteries are wired in series, so now you'll see 44.4 volts, current draw, and watts usage as a complete system.

I'll try to load the graph page and possibly the actual file as it comes out of the datalogger. You'll need to download this program from Eagletree to view it, http://eagletreesystems.com/Support/apps.htm ._________________Chris Bergen
Bergen R/C Helicopters

Thanks - I ported the data into excel to look at it. That datalogger is pretty slick. Anyway, I tried to attach a jpeg of the plot to the response but lost both in the process. So this response will go sans images.

Anyway, lets look at t=141700 ms (2.36 minutes). The voltage is 44.5 V and the current draw is 32 A. From P=IV, the power is 1424 W (roughly 2 hp). The average power draw for the entire 10 minute run was 1305 W.

I don't have a gut sense - does this seem reasonable? What is the power rating of the typical engine for this craft? I assume it would need to be 2-3 hp.

The gear ratio will be dictated by the motor and battery setup that the customer will ultimately use.

This is why we are testing different motors, to find the optimal setup for each "Popular" motor, and give the customer the option of what they want to use.

The Hacker A50 and the Actro 32-4 required different ratios to get the amp draw down to a reasonable level in an effort to keep flight time to a maximum._________________Chris Bergen
Bergen R/C Helicopters

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